The invention relates to the design of selectively operable friction clutches in a marine transmission to provide forward and reverse drives to the propeller shaft of a vessel.
U.S. Pat. No. 2,851,895 Aschauer describes a marine transmission drive that has been extensively used. It is intended that the gearing and clutch locations shown on U.S. Pat. No. 2,851,895 be utilized for this invention. These gear and shaft locations are shown on end view FIG. 3. Clutches are mounted on the input shaft and countershaft in transverse coplanar relationship, shown on FIGS. 1 and 2 of U.S. Pat. No. 2,851,895.
U.S. Pat. No. 2,851,895 describes a marine reverse and reduction gear. FIG. 1 shows how input power from an engine drives two input members of multiple plate oil lubricated friction clutches in reverse rotations, as shown by FIGS. 2 and 3. The output of an engaged clutch drives pinion 35 for forward and pinion 58 for reverse. The pinions mesh with output gear 36 on shaft 37 to drive a propeller either forward or reverse. Cooling oil passes through small holes in the input members plates drive.
It is to be noted the clutches utilized in the aforementioned patent are engaged by applying oil pressure to rotating annular pistons housed in their respective cylinders. The engaging system requires numerous components, as a pump, pressure regulating valve, control valve, and seals to transfer oil from the stationary components into the rotating clutches, as shown in FIG. 4 of U.S. Pat. No. 2,851,895. Erratic clutch behavior may result between a control signal and clutch actuation resulting from time and pressure losses between the control valve and clutch cylinders. It is desirable to have a clutch move into engagement quickly and have a torque rise programmed to provide a near constant level of energy absorption instead of potentially damaging peaks.
The pump flow required for optimum clutch engagement and cooling at lower engaging engine speeds rises at full engine speed since the pump is engine driven and results in power loss.
It is planned that the invention's electric engaging motor provides torque using minimal power input.